The invention relates to a rewinding machine, in other words a machine for the production of rolls of weblike material, for examplexe2x80x94but not exclusivelyxe2x80x94rolls of paper, tissue paper or the like, for the subsequent production of small rolls of toilet paper, kitchen towel or other products in roll form.
More specifically, the present invention relates to a rewinding machine, preferably of the type known as peripheral or surface, that is to say where the roll being formed is maintained in rotation by means of contact with peripheral winding-up members, such as rollers, belts or equivalent elements. Furthermore, the present invention relates to a rewinding machine having extractable mandrels, that is to say wherein, at the completion of winding-up, the mandrels are extracted in order to obtain a roll having no mandrel or central winding-up core.
The invention also relates to a method of winding up for the production of rolls of weblike material, typicallyxe2x80x94but not exclusivelyxe2x80x94rolls of paper, tissue paper or the like.
In numerous sectors of industry, and in particular in the paper converting industry, it is frequently necessary to produce rolls of wound-up weblike material, for example rolls of paper, tissue paper or the like; in other technological sectors, the need arises to produce rolls of plastic film, fabric, nonwoven fabric and other materials in web form.
Especially in the production sector of tissue paper articles, such as rolls of toilet paper, kitchen towel or similar products, from large-diameter reels, produced in paper mills, rolls or logs are produced having a diameter equal to the diameter of the product intended for the end consumer and axial lengths greater than those of the finished article. These rolls or logs are subsequently cut orthogonally to their axis to produce the small rolls intended for consumption.
For the production of rolls of this type, use is commonly made of rewinding machines of the type known as peripheral, where the roll being formed is maintained in rotation and the weblike material is fed by means of rotating members or other moveable members which are in surface contact with the exterior of the roll being formed. Examples of rewinding machines are described and illustrated in U.S. Pat. Nos. 4,723,724, 4,856,725, 4,828,195, 4,962,897, 4,487,377, 4,931,130, 5,248,106, 5,368,252, GB-A-2 105 688 and WO-A-9 421 545.
According to another technology, the rolls are wound up on motor-driven mandrels. This is referred to as central winding. Examples of this technology are described in US-RE-2 835 3, U.S. Pat. Nos. 3,430,881, 3,532,572, 3,552,670.
Normally, the rolls are produced on a tubular cardboard core which then remains permanently within the roll and is cut together with the wound-up weblike material, so that a piece of tubular core remains in each of the individual rolls intended for the end consumer.
Special methods also exist for winding up rolls without a central core, where the finished roll takes on the appearance of a compact cylinder completely filled with weblike material. Rewinding machines which operate in accordance with this principle are described in U.S. Pat. Nos. 5,639,046, 5,690,296, 5,839,680, 5,538,199.
Winding-up systems have also been studied in which the weblike material is wound up on a central core or mandrel to form the roll from which the mandrel is subsequently extracted and recycled. This system makes it possible to operate with winding-up principles substantially similar to those used for winding up on cardboard cores, but eliminates the need to produce and consume tubular cardboard cores, with a consequent saving of materials and a reduction in the bulk of the machinery, in that the need for what are known as the xe2x80x9ctube-makersxe2x80x9d, in other words the machines that produce the cardboard cores from strips of cardboard, is eliminated. The mandrels extracted from the finished rolls are recycled from the extraction zone, located downstream of the rewinder, to the entry of the rewinder.
In this way, it is possible to carry out continuous high-speed production with a limited number of mandrels.
In order to facilitate extraction and achieve other advantages in terms of reduction of bulk and ease of manipulation, it has been suggested that the extractable mandrels should be produced in two parts, each of which is extracted from the appropriate end of the finished roll. A machine and a method of this type are described in WO-A-99/42 393.
When the rolls are formed on extractable mandrels, appropriate measures have to be taken to ensure that the initial length of the weblike material adheres to the outer surface of the winding-up mandrel. These measures have to permit easy subsequent extraction of the mandrel once winding-up has been completed. To this end, use may be made of pneumatic systems, air blowers, electrostatic charges or the like which attract the free length to and maintain if on the surface of the mandrel, their action ceasing at a subsequent stage of the winding-up cycle.
Systems have also been examined in which the outer surface of the mandrel is soaked with water, which should provide a sufficient adhesive action for the initial free length of the weblike material which is being wound up. The water is absorbed by the weblike material in the subsequent phase of winding-up, thus permitting the subsequent extraction of the mandrel from the finished roll.
The systems currently used to anchor the free initial length of the weblike material on the extractable mandrel are not always satisfactory, in that they can be used only with certain types of material, or because they provide an adhesive effect that is not always reliable, especially at high production speeds, so that they enforce a reduced speed.
It is an object of the present invention to provide a rewinding machine and a winding method, in particular and preferably (but not exclusively) of the peripheral type on extractable winding-up mandrels, which makes it possible to achieve an effective and reliable anchoring of the free length of the weblike material on the mandrel, without obstructing or otherwise causing problems in the subsequent phases of extraction of the mandrel from the finished roll.
This and further objects and advantages, which will become apparent to persons skilled in the art from reading the text that follows, are substantially achieved with a rewinding machine for the production of rolls of weblike material, comprising: a system of winding up on winding-up mandrels for the formation of said rolls; an extractor for separating the mandrels from the respective rolls formed thereon and in which is provided at least one washing device for washing said mandrels between the separation from the rolls and the start of winding-up.
When a rewinding machine with central winding-up is used, the mandrels are moved by a revolving turret or the equivalent to various stations, which include an adhesive application station, a winding-up station and a station for drawing the roll or log off the mandrel. In this case, the washing means may be disposed in a manner such as to operate along the path of the mandrels between the station for drawing off the roll and the station for application of the adhesive, or in one of those stations. They may comprise, for example, brushes, pads or the like which pass along the axial course of the mandrel. Alternatively, they may comprise a washing box having a tubular chamber (possibly subdivided into two parts) within which the mandrel slides.
Preferably, however, the invention is embodied on a peripheral rewinding machine. In this case, advantageously, a recirculating path for the mandrels is provided between an extractor, which extracts the mandrels from the finished rolls, and a feeder, which inserts them into a winding-up cradle. The washing means are disposed in an appropriate position along the path of the mandrels.
The provision of washing of the mandrels extracted from the rolls makes it possible, first, to eliminate from the surface of the mandrels any residues of paper or other material that may continue to adhere to the mandrel after extraction.
The presence of the washing system makes it possible, and particularly advantageous, to use an adhesive to cause the initial free length of the weblike material to adhere reliably and quickly to the mandrel at the start of the winding-up of each roll. Any residue of adhesive on the extracted and recycled mandrel can be removed by means of the washing system.
The washing system makes it possible to use extractable mandrels in a traditional rewinder, in other words one designed to operate with tubular cardboard cores and the use of adhesive. It is thus possible to convert existing machines with minor modification operations. It is also possible to produce machines that can operate either with extractable mandrels or with tubular cores of cardboard (or other material) intended to remain within the finished product.
This is not possible in the absence of a washing system, since in that case debris would accumulate on the extractable mandrels.
It is not, however, necessary for the mandrels to be washed during each winding-up cycle. It would be possible, for example, to provide for washing every xe2x80x9cNxe2x80x9d winding-up cycles, where xe2x80x9cNxe2x80x9d depends, for example, on the type of adhesive and of weblike material.
Washing may take place by means of a washing fluid, for example water or water with added detergents, or even by means of a vapour, for example saturated steam, or by means of any other appropriate (liquid or gaseous) fluid.
The adhesive is preferably applied to the mandrel before insertion thereof into the zone where it comes into contact with the weblike material. However, the possibility is not ruled out that the adhesive is applied to the weblike material in the zone thereof intended to come into contact with the winding-up mandrel.
The washing device may be produced in various ways. For example, provision may be made to unload the mandrels into a tank containing a washing liquid, for example even ordinary water, with the possible addition of a detergent or a solvent. A stirrer may be provided to cause movement of the mandrels in the tank and facilitate the removal of the debris and residues of adhesive. Alternatively, brush means or other mechanical means may be provided which act on the surface of the mandrels located in the tank. From here, the mandrels can be extracted and transported into the winding-up zone, with or without a previous drying phase.
In general, the mandrels may be produced in a single piece or in two pieces that can be coupled and uncoupled. Washing may be performed either on the mandrels in a single piece or on the mandrels in two pieces, or possibly on the two separate pieces which are subsequently coupled or placed side by side (after washing) to form the mandrel. The possibility is not ruled out that the mandrels are produced in more than two pieces. When the pieces into which the mandrel is subdivided are washed separately, two washing devices may be provided, or a single washing device may be provided in which the various parts into which the mandrels are subdivided come together to be washed.
According to a particularly advantageous embodiment of the invention, the washing device comprises at least one tubular washing chamber through which the mandrels or parts thereof are passed and in which washing members are disposed. These washing members may be of various types and are preferably disposed in a circular arrangement to act on the entire surface of the mandrels or parts of mandrels which pass through the tubular chamber. For example, brushes or washing pads of annular shape may be provided, if appropriate associated with dispensers for a liquid or other washing fluid disposed upstream or in the same position as the brushes or pads. Preferably, however, the washing members are produced in a manner such as to have no mechanical contact with the surface of the mandrels or parts of mandrels. In a particularly advantageous embodiment, the latter comprise a series of nozzles which spray a liquid under pressure or blow a gaseous medium. In this way, no friction force is exercised on the mandrels or mandrel parts which could make it difficult for them to move forward. The nozzles may even be oriented in a manner such that the jet generated thereby helps to drive the mandrels or parts thereof forward. The possibility is not ruled out that the washing means are of the contact type, but equipped with a movement system, in a manner such as to generate a thrust in the forward direction of the mandrels. However, a solution of this type is more complex and less efficient from the standpoint of removal of the debris from the surface of the mandrels.
Although as a matter of principle it is possible to introduce the washed mandrels into the rewinding machine even without drying them, in particular when the washing fluid is a liquid, according to a preferred embodiment of the invention drying systems are provided which may be disposed, for example, within the chamber in which the mandrels or parts thereof pass. The drying system may comprise mechanical members, for example of absorbent material, which touch the surface of the mandrels or parts thereof. Preferably, however, for drying as well, a system is preferred that does not touch the surface of the mandrels, for example a suction member acting on the surface of the mandrels or parts of mandrels passing through the washing chamber.
Further advantageous possible features of the machine and method according to the invention are indicated in the appended claims and will be described in detail with reference to a possible form of embodiment.